This invention relates to the catalytic, oxidative dehydrogenation of saturated carboxylic acids to their corresponding unsaturated acids. More particularly, it is directed to the production of unsaturated carboxylic acids such as methacrylic acid from saturated carboxylic acids such as isobutyric acid utilizing promoted iron phosphorus oxide catalysts.
The production of unsaturated carboxylic acids from their corresponding saturated acids using iron phosphorus oxide catalysts, with or without various promoters, is disclosed in the art.
U.S. Pat. No. 3,948,959 discloses the preparation of unsaturated acids by oxidation of the corresponding saturated acid using iron phosphorus oxide catalysts promoted with Li, Na, K, Rb, Cs, Mg, Ca, Sr and Ba. U.S. Pat. Nos. 3,634,494; 3,652,654; 3,855,279; 3,917,673 and 4,029,695 disclose the preparation of unsaturated acids and esters from saturated acids and esters using iron phosphorus oxide catalysts, containing bismuth and/or lead promoters, optionally with other promoter elements, including Mn, U, Pr, Ca, Sr, and Cr. Prior art catalysts characteristically have exhibited short life and thermal instability.
It is therefore an object of the present invention to provide a process for the production of unsaturated acids from their corresponding saturated acids.
It is a further object of the invention to provide catalysts for said process having improved catalyst life and thermal stability.
It is a further object of the invention to provide catalysts for said process having improved activity and selectivity.